Characterization of silicon-on-insulator films recrystallized by an obliquely scanned pseudoline electron beam

Comprehensive and systematic studies on the growth characteristics of SOI (silicon-on-insulator) films recrystallized by an obliquely scanned pseudoline electron beam are presented. The obliquely scanned pseudoline beam was produced by scanning a spot electron beam along a line faster than the thermal response time of the substrate and it was moved as a whole to a different direction from the normal direction of the line. In the experiment of laterally seeded epitaxial growth of SOI films, the pseudoline beam was always scanned along the seed stripes, while the direction of the seed stripes to the Si substrate and an oblique angle between the scanning direction and the normal direction of the line were changed. It was found that the sub-boundary-free area in the SOI film was enhanced either by increasing the oblique angle or by rotating the seed direction from a 〈110〉 to 〈100〉 axis of the substrate. It was also found that the directions of sub-boundaries hardly depended on the oblique angle but they were governed by the crystal orientation of the substrate at a scanning velocity of 10 cm/s, while their directions were perpendicular to the pseudoline at the velocities below 1 cm/s. A simple model assuming formation of {111} facets at the solidification front is set up in order to explain these results.